Lewis-acidic Zr single-atom nanozyme with room-temperature glycosidase-like activity for cellulosic biomass degradation

Abstract

Efficient hydrolysis of robust chemical bonds under mild conditions remains a central challenge in catalysis and biomass valorization. Herein, we report a zirconium single-atom nanozyme anchored on nitrogen-doped carbon (Zr–NC) that exhibits remarkable catalytic activity toward the hydrolysis of β-1,4-glycosidic bonds. The Zr–N₄ coordination environment endows the isolated Zr centers with pronounced Lewis acidity, enabling effective polarization and activation of glycosidic bonds under ambient conditions. Using PNPG as a model substrate, Zr–NC demonstrates significantly enhanced hydrolytic activity compared to conventional zirconium oxide catalysts. Density functional theory (DFT) calculations reveal that the strong Lewis acidic character of the Zr–N₄ site facilitates charge redistribution within the glycosidic bond, lowering the activation barrier for nucleophilic attack by water. Moreover, the single-atom configuration suppresses excessive water coordination, maintaining an optimal balance between substrate adsorption and catalytic turnover. As a result, Zr–NC enables efficient depolymerization of cellulose-rich biomass, achieving effective degradation of corn stover under mild conditions. This work highlights the potential of single-atom nanozymes as robust and tunable Lewis acid catalysts for biomass conversion and sustainable catalysis.